65 resultados para 765

em Chinese Academy of Sciences Institutional Repositories Grid Portal


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综述了热轧钢板织构的形成机制和形成特点,分析了化学成分、加热温度、终轧温度、轧制速度、轧后冷却速度以及润滑对热轧织构的影响规律,并描述了热轧织构对热轧钢板塑性应变比、屈服强度和韧性的影响特点,可为热轧钢板织构和性能的优化与控制提供依据。

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采用直接斜率控制法完整地实现了对自适应光学(AO)系统的数值模拟,系统研究了带自适应光学校正的激光大气传输规律。提出了对计算出的位相进行“剪接”的办法,解决了残余位相方差与自适应光学的校正效果没有对应关系的问题。证明可以把快速傅里叶变换法(FFT)用于透镜成像的聚焦计算,与积分法得到相同的结果。报道了对于一定的延迟时间,当大气横向风速大于一个阈值时,自适应光学补偿比完全相位补偿的效果还要好,表明在一定的条件下自适应光学系统的校正能力并非越大越好

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The influence of inertial, thermal and rate - sensitive effects on the void growth at high strain rate in a thermal - viscoplastic solid is investigated by means of a theoretical model presented in the present paper. Numerical analysis of the model suggests that inertial, thermal and rate - sensitive effects are three major factors which greatly influence the behavior of void growth in the high strain rate case. Comparison of the mathematical model proposed in the present work and Johnson's model shows that if the temperature - dependence is considered, material viscosity eta can take the experimentally measured values.

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Lattice-matched (Delta(a/a) = 1.8-3.4%) (001) LiGaO2 substrates have been employed for the first time to grow ZnO thin films by pulsed-laser deposition at 350-650 degrees C with oxygen partial pressure of 20Pa. XRD shows that a highly c-axis-oriented ZnO film can be deposited on (001) LiGaO2 substrate at 500 degrees C. AFM images reveal the surfaces of as-deposited ZnO films are smooth and root-mean-square values are 6.662, 5.765 and 6.834 nm at 350, 500 and 650 degrees C, respectively. PL spectra indicate only near-band-edge UV emission appears in the curve of ZnO film deposited at 500 degrees C. The deep-level emission of ZnO film deposited at 650 degrees C probably results from Li diffusion into the film. All the results illustrate substrate temperature plays a pretty important role in obtaining ZnO film with a high quality on LiGaO2 substrate by pulsed-laser deposition. (c) 2006 Elsevier B.V. All rights reserved.

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本文分析了在不同衬底上生长无极性GaN薄膜的情况,这些衬底主要包括γ-LiAlO2、r面蓝宝石等。通常在蓝宝石上制备的GaN外延膜是沿c轴生长的,而c轴是GaN的极性轴,导致GaN基器件有源层量子阱中出现很强的内建电场,发光效率会因此降低,发展非极性面外延,有望克服这一物理现象,使发光效率提高。

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A new kind of Nd3+, -doped high silica glass (SiO2 > 96% (mass fraction)) was obtained by sintering porous glass impregnated with Nd3+, ions. The absorption and luminescence properties of high silica glass doped with different Nd3+, concentrations were studied. The intensity parameters Omega(t) (t = 2, 4, 6), spontaneous emission probability, fluorescence lifetime, radiative quantum efficiency, fluorescence branching ratio, and stimulated emission cross section were calculated using the Judd-Ofelt theory. The optimal Nd3+ concentration in high silica glass was 0.27% (mole fraction) because of its high quantum efficiency and emission intensity. By comparing the spectroscopic parameters with other Nd3+ doped oxide glasses and commercial silicate glasses, the Nd3+-doped high silica glasses are likely to be a promising material used for high power and high repetition rate lasers.

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麻疯树(Jatropha curcas L.)属大戟科麻疯树属多年生亚乔木,耐干旱、高温和贫瘠等,具很强的抗逆性,在干热河谷等边际土地上生长良好。其种子富含油脂,是制备生物柴油的理想材料,为重要的能源植物之一。油体(oil body)是种子细胞中重要的细胞器, 脂肪酸以三脂酰甘油(triacylglyeerols,TAG)的形式储存其内,是种子萌发和幼苗生长时所需碳骨架和能量的主要来源。种子萌发为生命萌动并构建成自养个体的过程,是高等植物生长发育中的重要事件。 本论文运用高通量的蛋白质组学研究手段,结合电镜技术和生理学分析,对麻疯树种子油体以及种子萌发过程中蛋白质表达、生理学响应和细胞结构变化进行了研究。 从麻疯树种子胚乳中分离油体,再从油体中提取蛋白,经双向凝胶电泳后,得到油体蛋白质组的二维表达谱,这些蛋白质主要分布在等电点5 ~ 10、分子量12 ~ 66 kDa的范围内;图像分析表明,油体蛋白质组至少有141个蛋白点,其中酸性蛋白74个,碱性蛋白67个,表达丰度较高的多为低分子量碱性蛋白。对其中36个重要蛋白点进行LC-MS/MS质谱分析,得到鉴定的蛋白分别为30个基因的表达产物,主要包括油体重要的结构蛋白油质蛋白(oleosin)和caleosin,麻疯树种子毒蛋白curcin,以及新鉴定得到的另一种可能的麻疯树种子毒蛋白,人体过敏反应蛋白橡胶延伸因子(REF)。还有四个与脂肪酸代谢相关的酶,其中3-羟酰-酰基载体蛋白(ACP)脱水/催化酶和醇酰基转移酶与脂肪酸合成有关,而脂氧合酶和磷脂酶D在脂肪酸降解中发挥作用,显示部分脂肪酸代谢相关的酶在油体储存状态就已附着在油体上,为种子萌发时动员油脂做好了准备。 麻疯树种子胚乳发达,在32℃湿润土壤中很快就会萌动,胚轴伸长露出胚根,长出新根,约4天后形成出土子叶幼苗。种子萌发过程中胚乳主要成分含量测定表明,含水量在前24小时迅速上升,至48小时增加缓慢,此后开始较快上升,可分为三个阶段,呈现“S”型的变化;粗脂肪和粗蛋白在前两个阶段变化不大,进入第三阶段后其含量迅速下降,前者先于后者,分别在萌发后72小时和96小时后开始明显减少,说明被大量降解、转化,供萌发生长利用,其中主要组分亚油酸最为明显。细胞超微结构观察发现,排列整齐充满整个胚乳细胞的油体和嵌合在油体中的蛋白储存泡在种子萌发过程中,随着线粒体、乙醛酸循环体和液泡的出现增多或增大而被逐渐解体、减少或消失;同时,发现脂肪酸主要在乙醛酸循环体、蛋白颗粒主要在液泡中被降解或转化。 蛋白质组学分析表明,麻疯树种子在萌发72小时过程中变化量在两倍以上的差异蛋白点共有141个,所有的差异蛋白均通过LC-MS/MS分析和NCBI蛋白数据库搜索得到鉴定。其中包括多个参与降解储藏油脂的酶,如乙醛酸循环途径中的顺乌头酸酶,异柠檬酸裂解酶和苹果酸脱氢酶等,均从种子萌发48小时开始表达量明显上升;葡糖异生途径中的酶在种子萌发中的积累略晚于乙醛酸循环途径,如烯醇酶,磷酸甘油酸变位酶,磷酸甘油酸激酶,磷酸丙糖异构酶和醛缩酶大多在萌发约60小时后表达量开始上调。分析结果表明,乙醛酸循环途径在种子萌发48小时后被激活,与电镜观察胚乳细胞发现油脂在萌发48小时时开始被动员相一致,因而大规模的油脂动员开始于种子萌发的第三阶段。 同时,蛋白质组学的分析结果也得到了种子胚乳组分变化分析及电镜观察结果的印证。超微细胞结构观察显示种子储藏蛋白降解在萌发第二阶段启动,主要在液泡中进行降解。粗脂肪的含量在72小时时显著降低,而电镜观察显示此时胚乳细胞中出现中央大液泡,出现大量的线粒体和乙醛酸循环体,细胞结构发生重大变化,萌发96小时后仅有少量油体残留于胚乳细胞中,这些都为储藏油脂在麻疯树种子萌发过程中的降解方式提供了重要证据。许多其他的功能蛋白在种子萌发过程中也发生了变化,表明种子萌发过程中不仅发生储藏物质的动员,也发生抗逆反应以及植物形态的构建等众多其他生理生化反应。 本研究首次对麻疯树种子油体进行了蛋白组成分析,并结合电镜技术及生理分析深入探讨了种子储藏物质在萌发中的降解方式,为更好的理解油体结构、木本油料种子的萌发机制和对麻疯树进行品种的改良提供了参考。

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A blood coagulation factor IX-binding protein (TSV-FIX-BP) was isolated from the snake venom of Trimeresurus stejnegeri. On SDS-polyacrylamide gel electrophoresis, TSV-FIX-BP showed a single band with an apparent molecular weight of 23,000 under non-reducing conditions. and two distinct bands with apparent molecular weights of 14,800 and 14,000 under reducing conditions. cDNA clones containing the coding sequences of TSV-FIX-BP were isolated and sequenced to determine the structure of the precusors of TSV-FIX-BP subunits. The deduced amino acid sequences of two subunits of TSV-FIX-BP were confirmed by N-terminal protein sequencing and trypsin-digested peptide mass fingerprinting. TSV-FIX-BP was a nonenzymatic C-type lectin-like anti-coagulant. The anti-coagulant activity of TSV-FIX-BP was mainly caused by its dose dependent interaction with blood coagulation factor IX but not with blood coagulation factor X. (C) 2003 Elsevier Science Ltd. All rights reserved.

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The ability to feed on vertebrate blood has evolved many times in various arthropod clades. Consequently, saliva of blood-feeding arthropods has proven to be a rich source of antihemostatic molecules. A variety of platelet aggregation inhibitors antagonize platelet responses to wound-generated signals, including ADP, thrombin, and collagen. Anticoagulants disrupt elements of both the intrinsic and extrinsic pathways. Vasodilators include nitrophorins (nitric oxide storage and transport heme proteins), a variety of peptides that mimic endogenous vasodilatory neuropeptides, and proteins that catabolize or sequester endogenous vasoconstrictors. Multiple salivary proteins may be directed against each component of hemostasis, resulting in both redundancy and in some cases cooperative interactions between antihemostatic proteins. The complexity and redundancy of saliva ensures an efficient blood meal for the arthropod, but it also provides a diverse array of novel antihemostatic molecules for the pharmacologist.